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Professor Wang Bo publishes research achievements in the journal Angew. Chem. Int. Ed

release date :2018-12-16 03:02:00  |   [ close window ]ViewCount:

    Translator:  Han Yu, News Agency of BIT

    Editor:  News Center of BIT

  Recently, an iron-containing metal-organic framework, MIL-100(Fe), which could be used for ozone removal, was jointly proposed by Prof Wang Bo, Prof Chen Shilv and team of assistant professor Ma Xiaojie (co-author of the correspondence). Related findings were published in the international top journal Angew. Chem. Int. Ed. under the title "An Iron-Containing Metal-Organic Framework as a Highly Efficient Catalyst for Ozone Decomposition".

  MIL-100(Fe) exhibits long-lasting ozone conversion efficiency of 100% within 100 h under the condition of relative humidity of 45% and space velocity of 1.9×105 h−1 at room temperature, which outperforms many adsorbents catalysts like activated carbon and α‐MnO2 (drop to 18% and 60% of ozone decomposition, respectively after 12 h). More importantly, they found that water plays a synergetic role in ozone decomposition catalyzed by MOFs, and total ozone removal is realized even under extremely wet conditions (e.g. , >90% RH). For further practical applications, a MOF-based catalytic filter is also fabricated by processing MIL-100(Fe) in a hot-processing (HoP) method; as a filter in a mask it shows almost complete protection against low-level ozone. This study demonstrates the promising potential of MOF in ozone pollution control, and provides new insights into the design of ozone decomposition catalysts.

  Ground‐level ozone is one of the major air pollutants, and leads directly to photochemical smog owing to its high reactivity and strong oxidation potential. Long‐term exposure to ozone can cause serious lung damage and raise the risk of death from respiratory diseases. The main approaches for ozone removal include activated carbon adsorption, chemical absorption, and catalytic decomposition. The inevitable problems of sorbent regeneration and liquid waste disposal mean that heterogeneous catalysis is currently considered as the most effective method.(Heterogeneous catalysis is considered as the most effective method due to the inevitable problems in sorbent regeneration and liquid waste disposal)

  So far, noble metals, or transition metal oxides are used as catalysts for ozone elimination. Among these reported catalysts, MnO2 appears to be the most promising, with good decomposition activity and low cost. However, its activity would decrease when oxygen species accumulates on surface. More importantly, MnO2 shows depressed activity in the presence of water vapor owing to the competitive adsorption of water on reactive sites. Although much effort has been focused on noble‐metal‐based catalysts to achieve good activity in high humidity, the large‐scale application is limited because of the high cost and scarcity. Therefore, it is highly desirable to develop non‐noble‐metal‐based catalysts with outstanding activities and stable performance in humid environments.

  Figure 1
MIL‐100(Fe) as catalyst for ozone decomposition.

  Figure 2
a) Ozone conversion on MIL‐100(Fe). b) Powder XRD patterns of simulated, as‐synthesized, and ozone‐exposed MIL‐100(Fe).

c) N2 sorption isotherms of MIL‐100(Fe) before and after exposure to ozone. Inset: pore size distribution of MIL‐100(Fe).

d) Ozone conversion on MIL‐100(Fe), α‐MnO2, activated carbon, α‐Fe2O3, and β‐MnO2, respectively. Conditions: 0.03 g catalysts diluted with 0.27 g quartz sand, C (O3)=45 ppm, flow rate=1000 mL min−1, RH=45 %, room temperature.